Let's use a dictionary to keep track of how many times the user entered each value...

watcher_dict = {} # a new empty dict
while True:
user_data = raw_input()
if not user_data: # enter no data to...
break # end the loop
tree_maker(user_data)
# record the user_data into watcher_dict
if user_data in watcher_dict: # if it is already in the dict
watcher_dict[user_data] += 1 # then add 1 to it
else: # if it is not yet in the dict
watcher_dict[user_data] = 1 # then set it to 1
print('watcher_dict:', watcher_dict)